A useful rule of thumb in politics is never to utter a phrase which, were you to insert "not" or "don't" into it, would transform it into something a lunatic might say. If a statement's opposite cannot imaginably be said, then the statement itself need not be said either.

When the Shadow Chancellor George Osborne turned up at the Labour think-tank Demos in August, he demonstrated, by way of platitudes designed to win over the Blairites, the modern Conservative Party's platform. "Let me start by laying my own cards on the table," he offered, generously. "My politics are unapologetically progressive." As I have pointed out here before, the opposite of this phrase would not be said. Nor would the opposite of any of his follow-on babble. Try inserting "not" here:

"I am optimistic about the potential of individuals to transform their lives, and society, for the better."

Or: "I am excited by the huge potential of technological and scientific innovation to enhance opportunity."

In the weeks since Westminster first lay prone in a state of post-expenses shock, it was said that the House might reform itself. The Conservatives put it around that David Cameron's response to the scandal was more "assertive" than Gordon Brown's. What Cameron actually did was just what Brown did — he protected the pickpockets he needed and discarded a few he didn't.

Westminster's first post-expenses test was to select a new Speaker. In an effort to frustrate the Conservatives, Labour supported the egregious Tory expenses-fiddler John Bercow. He proceeded to demonstrate the exciting new era of change by doing what everyone does when they want to demonstrate an exciting new era of change: he dressed down a bit.

The first post-expenses by-election in Norwich North saw the Conservatives boast that they were putting up an entirely new type of politician to represent "change". Chloe Smith may yet do good things, but it appeared as though the Tories were under the misapprehension that women were unheard of in politics. I know the Cameroons would like to forget Margaret Thatcher but that really doesn't mean the rest of us have done so.

And to top it off and remind us why we like to leave the country in August, we had the special pleading of the Shadow Leader of the House Alan Duncan — who thanks to his work in the oil industry for the convicted fraudster Marc Rich is himself one of the richest members of the House. Though not too rich apparently, because he was revealed to have said that MPs like himself were "forced to live on rations". Of course, he issued an instant apology — once he was found out.

I have long believed that the comprehensive decline of our political life can be traced to Diane Abbott. The incomparably patronising Labour backbencher is best known for sitting perilously close to Michael Portillo once a week on the BBC's This Week studio. But what she should be known for is being the initiator of the modern politician's belief that confessing to a crime is the same thing as doing time for it. I am thinking of the delightful moment in 2003 when Abbott, who had spent her life criticising other parents who refused to send their children to the UK's failing state school system, sent her son to a fee-paying school. Asked how she could justify this hypocrisy, she explained that she couldn't. What she had done was hypocritical and that was that. She wanted the best for her son, she said (as though other parents did not).

The Abbott episode signalled the beginning of an era in which the political class found only rewards in their job and no punishment for failure or wrongdoing. Even hypocrisy or theft, if confessed to, could be forgiven. Cameron handed the taxpayer a bill to have his wisteria cleared. Once he was caught, he said, "Sorry" — as though apologising mitigated the deceit.

Like much of the country, I spent what little summer we had mulling on the bleakness of all this. While doing so, I read Ruth Dudley-Edwards's Aftermath: The Omagh Bombing and the Families' Pursuit of Justice (Harvill Secker). Harrowing and upsetting, it is also inspiring. Reading it gave me the first glimmer of a way out of the horrible failure of our political class.

What we need are people such as those revealed by Dudley-Edwards — decent ordinary folk who have been let down by every arm of the state. It seems to me that we will have to find inspiration and example in civic leaders. We will have to show our political leaders that we expect those we pay to be in public life to demonstrate real principles and actual decency. This might well not be a "progressive" ideal. It might even be old-fashioned. Perhaps I can suggest the starting of a movement. What we need is a movement which is not merely regressive, but unapologetically so.